Cannot login as another user

Cannot login as another user

Hi I have two email addresses therefore two users -  liz@redladysa.com.au and elizabeth@redladysa.com.au
however, whenever I open zoho mail, it automatically logs me in as Liz and I can't login as elizabeth in order to check emails coming to that address. The help section says that I can use a unified interface, but it doesn't tell me how.
Thanks